This invention relates to joining technology generally, and specifically, to a welding method for joining components fabricated of high gamma prime superalloys.
Rene 108 is one superalloy that is becoming a desired material of choice for blades, nozzles, and shrouds in advanced gas turbines. Rene 108 and other high gamma prime superalloys have excellent mechanical and oxidation properties at elevated temperatures. However, Rene 108 and other high gamma prime superalloys have poor weldability and are some of the hardest to weld materials in the superalloy category. Welding on Rene 108 or other high gamma prime superalloys using any traditional welding procedures results in significant cracking in the weld metal and base metal heat affected zone. Laser welding or laser hybrid welding of Rene 108 and other high gamma prime superalloys generates undesirable cracks along the weld line. Generally, the cracks produced from laser welding are perpendicular to the welding joint. Undesirable cracks along the weld line lead to unacceptable welds.
In the past, known methods have attempted to use a ductile material over the weld. However, cracking still occurred after welding. Other methods have used a braze over the weld, but again cracking was a problem. The inevitable cracks in the base metal or filler material could never be successfully filled. To date, no suitable method has been disclosed for successfully welding high gamma prime superalloys, such as Rene 108.